81936918 has 36 divisors (see below), whose sum is σ = 206516700. Its totient is φ = 23410296.

The previous prime is 81936917. The next prime is 81936929. The reversal of 81936918 is 81963918.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81936917) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 45568 + ... + 47331.

It is an arithmetic number, because the mean of its divisors is an integer number (5736575).

Almost surely, 2^81936918 is an apocalyptic number.

81936918 is an abundant number, since it is smaller than the sum of its proper divisors (124579782).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81936918 is a wasteful number, since it uses less digits than its factorization.

81936918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92921 (or 92911 counting only the distinct ones).

The product of its digits is 93312, while the sum is 45.

The square root of 81936918 is about 9051.9013472309. The cubic root of 81936918 is about 434.3367140695.

Subtracting 81936918 from its reverse (81963918), we obtain a cube (27000 = 30³).

The spelling of 81936918 in words is "eighty-one million, nine hundred thirty-six thousand, nine hundred eighteen".